The LOCALIO auxiliary RPC protocol consists of a single "UUID_IS_LOCAL"
RPC method that allows the Linux NFS client to verify the local Linux
NFS server can see the nonce (single-use UUID) the client generated and
made available in nfs_common for subsequent lookup and verification
by the NFS server. If matched, the NFS server populates members in the
nfs_uuid_t struct. The NFS client then transfers these nfs_uuid_t
struct member pointers to the nfs_client struct and cleans up the
nfs_uuid_t struct. See: fs/nfs/localio.c:nfs_local_probe()
This protocol isn't part of an IETF standard, nor does it need to be
considering it is Linux-to-Linux auxiliary RPC protocol that amounts
to an implementation detail.
Localio is only supported when UNIX-style authentication (AUTH_UNIX, aka
AUTH_SYS) is used (enforced by fs/nfs/localio.c:nfs_local_probe()).
The UUID_IS_LOCAL method encodes the client generated uuid_t in terms of
the fixed UUID_SIZE (16 bytes). The fixed size opaque encode and decode
XDR methods are used instead of the less efficient variable sized
methods.
Having a nonce (single-use uuid) is better than using the same uuid
for the life of the server, and sending it proactively by client
rather than reactively by the server is also safer.
[NeilBrown factored out and simplified a single localio protocol and
proposed making the uuid short-lived]
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Co-developed-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
fs/nfs/client.c | 6 ++-
fs/nfs/localio.c | 136 +++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 135 insertions(+), 7 deletions(-)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index b981c519a12d..6a4b605cc943 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -434,8 +434,10 @@ struct nfs_client *nfs_get_client(const struct nfs_client_initdata *cl_init)
list_add_tail(&new->cl_share_link,
&nn->nfs_client_list);
spin_unlock(&nn->nfs_client_lock);
- nfs_local_probe(new);
- return rpc_ops->init_client(new, cl_init);
+ new = rpc_ops->init_client(new, cl_init);
+ if (!IS_ERR(new))
+ nfs_local_probe(new);
+ return new;
}
spin_unlock(&nn->nfs_client_lock);
diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
index fa598b99941a..40521da422f7 100644
--- a/fs/nfs/localio.c
+++ b/fs/nfs/localio.c
@@ -50,18 +50,77 @@ static void nfs_local_fsync_work(struct work_struct *work);
static bool localio_enabled __read_mostly = true;
module_param(localio_enabled, bool, 0644);
+static inline bool nfs_client_is_local(const struct nfs_client *clp)
+{
+ return !!test_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
+}
+
bool nfs_server_is_local(const struct nfs_client *clp)
{
- return test_bit(NFS_CS_LOCAL_IO, &clp->cl_flags) != 0 &&
- localio_enabled;
+ return nfs_client_is_local(clp) && localio_enabled;
}
EXPORT_SYMBOL_GPL(nfs_server_is_local);
+/*
+ * UUID_IS_LOCAL XDR functions
+ */
+
+static void localio_xdr_enc_uuidargs(struct rpc_rqst *req,
+ struct xdr_stream *xdr,
+ const void *data)
+{
+ const u8 *uuid = data;
+
+ encode_opaque_fixed(xdr, uuid, UUID_SIZE);
+}
+
+static int localio_xdr_dec_uuidres(struct rpc_rqst *req,
+ struct xdr_stream *xdr,
+ void *result)
+{
+ /* void return */
+ return 0;
+}
+
+static const struct rpc_procinfo nfs_localio_procedures[] = {
+ [LOCALIOPROC_UUID_IS_LOCAL] = {
+ .p_proc = LOCALIOPROC_UUID_IS_LOCAL,
+ .p_encode = localio_xdr_enc_uuidargs,
+ .p_decode = localio_xdr_dec_uuidres,
+ .p_arglen = XDR_QUADLEN(UUID_SIZE),
+ .p_replen = 0,
+ .p_statidx = LOCALIOPROC_UUID_IS_LOCAL,
+ .p_name = "UUID_IS_LOCAL",
+ },
+};
+
+static unsigned int nfs_localio_counts[ARRAY_SIZE(nfs_localio_procedures)];
+static const struct rpc_version nfslocalio_version1 = {
+ .number = 1,
+ .nrprocs = ARRAY_SIZE(nfs_localio_procedures),
+ .procs = nfs_localio_procedures,
+ .counts = nfs_localio_counts,
+};
+
+static const struct rpc_version *nfslocalio_version[] = {
+ [1] = &nfslocalio_version1,
+};
+
+extern const struct rpc_program nfslocalio_program;
+static struct rpc_stat nfslocalio_rpcstat = { &nfslocalio_program };
+
+const struct rpc_program nfslocalio_program = {
+ .name = "nfslocalio",
+ .number = NFS_LOCALIO_PROGRAM,
+ .nrvers = ARRAY_SIZE(nfslocalio_version),
+ .version = nfslocalio_version,
+ .stats = &nfslocalio_rpcstat,
+};
+
/*
* nfs_local_enable - enable local i/o for an nfs_client
*/
-static __maybe_unused void nfs_local_enable(struct nfs_client *clp,
- nfs_uuid_t *nfs_uuid)
+static void nfs_local_enable(struct nfs_client *clp, nfs_uuid_t *nfs_uuid)
{
spin_lock(&clp->cl_localio_lock);
@@ -103,11 +162,77 @@ void nfs_local_disable(struct nfs_client *clp)
spin_unlock(&clp->cl_localio_lock);
}
+/*
+ * nfs_init_localioclient - Initialise an NFS localio client connection
+ */
+static struct rpc_clnt *nfs_init_localioclient(struct nfs_client *clp)
+{
+ struct rpc_clnt *rpcclient_localio;
+
+ rpcclient_localio = rpc_bind_new_program(clp->cl_rpcclient,
+ &nfslocalio_program, 1);
+
+ dprintk_rcu("%s: server (%s) %s NFS LOCALIO.\n",
+ __func__, rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR),
+ (IS_ERR(rpcclient_localio) ? "does not support" : "supports"));
+
+ return rpcclient_localio;
+}
+
+static bool nfs_server_uuid_is_local(struct nfs_client *clp,
+ nfs_uuid_t *nfs_uuid)
+{
+ u8 uuid[UUID_SIZE];
+ struct rpc_message msg = {
+ .rpc_argp = &uuid,
+ };
+ struct rpc_clnt *rpcclient_localio;
+ int status;
+
+ rpcclient_localio = nfs_init_localioclient(clp);
+ if (IS_ERR(rpcclient_localio))
+ return false;
+
+ export_uuid(uuid, &nfs_uuid->uuid);
+
+ msg.rpc_proc = &nfs_localio_procedures[LOCALIOPROC_UUID_IS_LOCAL];
+ status = rpc_call_sync(rpcclient_localio, &msg, 0);
+ dprintk("%s: NFS reply UUID_IS_LOCAL: status=%d\n",
+ __func__, status);
+ rpc_shutdown_client(rpcclient_localio);
+
+ /* Server is only local if it initialized required struct members */
+ if (status || !nfs_uuid->net || !nfs_uuid->dom)
+ return false;
+
+ return true;
+}
+
/*
* nfs_local_probe - probe local i/o support for an nfs_server and nfs_client
+ * - called after alloc_client and init_client (so cl_rpcclient exists)
+ * - this function is idempotent, it can be called for old or new clients
*/
void nfs_local_probe(struct nfs_client *clp)
{
+ nfs_uuid_t nfs_uuid;
+
+ /* Disallow localio if disabled via sysfs or AUTH_SYS isn't used */
+ if (!localio_enabled ||
+ clp->cl_rpcclient->cl_auth->au_flavor != RPC_AUTH_UNIX) {
+ nfs_local_disable(clp);
+ return;
+ }
+
+ if (nfs_client_is_local(clp)) {
+ /* If already enabled, disable and re-enable */
+ nfs_local_disable(clp);
+ }
+
+ nfs_uuid_begin(&nfs_uuid);
+ if (nfs_server_uuid_is_local(clp, &nfs_uuid))
+ nfs_local_enable(clp, &nfs_uuid);
+ nfs_uuid_end(&nfs_uuid);
}
EXPORT_SYMBOL_GPL(nfs_local_probe);
@@ -146,7 +271,8 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
case -ENOMEM:
case -ENXIO:
case -ENOENT:
- nfs_local_disable(clp);
+ /* Revalidate localio, will disable if unsupported */
+ nfs_local_probe(clp);
}
return NULL;
}
--
2.44.0
